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70-567: The boundary between MEO and LEO is an arbitrary altitude chosen by accepted convention, whereas the boundary between MEO and HEO is the particular altitude of a geosynchronous orbit , in which a satellite takes 24 hours to circle the Earth, the same period as the Earth’s own rotation. All satellites in MEO have an orbital period of less than 24 hours, with the minimum period (for a circular orbit at

140-431: A delta-v of approximately 50 m/s per year. A second effect to be taken into account is the longitudinal drift, caused by the asymmetry of the Earth – the equator is slightly elliptical ( equatorial eccentricity ). There are two stable equilibrium points sometimes called "gravitational wells" (at 75.3°E and 108°W) and two corresponding unstable points (at 165.3°E and 14.7°W). Any geostationary object placed between

210-427: A geostationary transfer orbit (GTO), an elliptical orbit with an apogee at GEO height and a low perigee . On-board satellite propulsion is then used to raise the perigee, circularise and reach GEO. Satellites in geostationary orbit must all occupy a single ring above the equator . The requirement to space these satellites apart, to avoid harmful radio-frequency interference during operations, means that there are

280-482: A geosynchronous transfer orbit (GTO), an elliptical orbit with an apogee at GSO height and a low perigee . On-board satellite propulsion is then used to raise the perigee, circularise and reach GSO. Once in a viable geostationary orbit, spacecraft can change their longitudinal position by adjusting their semi-major axis such that the new period is shorter or longer than a sidereal day, in order to effect an apparent "drift" Eastward or Westward, respectively. Once at

350-515: A latency (delay) five times lower than on the existing platform based on geostationary orbit satellites. In September 2023, satellite operator SES announced the first satellite internet service to use satellite constellations in both MEO and Low Earth Orbit (LEO) . The SES Cruise mPOWERED + Starlink service will use SES's O3b mPOWER MEO satellites and SpaceX 's Starlink LEO system to provide cruise ship passengers with internet, social media and video calls at up to 3 Gbps per ship anywhere in

420-452: A temporary orbit , and placed in a slot above a particular point on the Earth's surface. The orbit requires some stationkeeping to keep its position, and modern retired satellites are placed in a higher graveyard orbit to avoid collisions. In 1929, Herman Potočnik described both geosynchronous orbits in general and the special case of the geostationary Earth orbit in particular as useful orbits for space stations . The first appearance of

490-537: A geostationary orbit in popular literature was in October 1942, in the first Venus Equilateral story by George O. Smith , but Smith did not go into details. British science fiction author Arthur C. Clarke popularised and expanded the concept in a 1945 paper entitled Extra-Terrestrial Relays – Can Rocket Stations Give Worldwide Radio Coverage? , published in Wireless World magazine. Clarke acknowledged

560-415: A geostationary orbit in particular, it ensures that it holds the same longitude over time. This orbital period, T , is directly related to the semi-major axis of the orbit through the formula: where: The eccentricity is zero, which produces a circular orbit . This ensures that the satellite does not move closer or further away from the Earth, which would cause it to track backwards and forwards across

630-440: A geostationary orbit remains in the same position in the sky to observers on the surface. Communications satellites are often given geostationary or close-to-geostationary orbits, so that the satellite antennas that communicate with them do not have to move but can be pointed permanently at the fixed location in the sky where the satellite appears. In 1929, Herman Potočnik described both geosynchronous orbits in general and

700-525: A geostationary orbit was Syncom 3 , which was launched by a Delta D rocket in 1964. With its increased bandwidth, this satellite was able to transmit live coverage of the Summer Olympics from Japan to America. Geostationary orbits have been in common use ever since, in particular for satellite television. Today there are hundreds of geostationary satellites providing remote sensing and communications. Although most populated land locations on

770-459: A geosynchronous orbit. A further form of geosynchronous orbit is the theoretical space elevator . If a mass orbiting above the geostationary belt is tethered to the earth’s surface, and the mass is accelerated to maintain an orbital period equal to one sidereal day, then since the orbit now requires more downward force than is supplied by gravity alone. The tether will become tensioned by the extra centripetal force required, and this tension force

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840-487: A high inclination of 63.4° and high eccentricity of 0.722 with a period of 12 hours, so a satellite spends most of its orbit above the chosen area in high latitudes. This orbit was used by the (now defunct) North American Sirius Satellite Radio and XM Satellite Radio satellites and the Russian Molniya military communications satellites, after which it is named. Communications satellites in MEO include

910-399: A known position) and providing an additional reference signal. This improves position accuracy from approximately 5m to 1m or less. Past and current navigation systems that use geostationary satellites include: Geostationary satellites are launched to the east into a prograde orbit that matches the rotation rate of the equator. The smallest inclination that a satellite can be launched into

980-408: A large area of the earth's surface, extending 81° away in latitude and 77° in longitude. They appear stationary in the sky, which eliminates the need for ground stations to have movable antennas. This means that Earth-based observers can erect small, cheap and stationary antennas that are always directed at the desired satellite. However, latency becomes significant as it takes about 240 ms for

1050-516: A limited number of orbital slots available, and thus only a limited number of satellites can be operated in geostationary orbit. This has led to conflict between different countries wishing access to the same orbital slots (countries near the same longitude but differing latitudes ) and radio frequencies . These disputes are addressed through the International Telecommunication Union 's allocation mechanism under

1120-406: A signal to pass from a ground based transmitter on the equator to the satellite and back again. This delay presents problems for latency-sensitive applications such as voice communication, so geostationary communication satellites are primarily used for unidirectional entertainment and applications where low latency alternatives are not available. Geostationary satellites are directly overhead at

1190-431: Is a four-satellite system that operates in a geosynchronous orbit at an inclination of 42° and a 0.075 eccentricity. Each satellite dwells over Japan , allowing signals to reach receivers in urban canyons then passes quickly over Australia. Geosynchronous satellites are launched to the east into a prograde orbit that matches the rotation rate of the equator. The smallest inclination that a satellite can be launched into

1260-557: Is a single point on the equator . In the general case of a geosynchronous orbit with a non-zero inclination or eccentricity , the ground track is a more or less distorted figure-eight, returning to the same places once per sidereal day. Geostationary satellite A geostationary orbit , also referred to as a geosynchronous equatorial orbit ( GEO ), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator , 42,164 km (26,199 mi) in radius from Earth's center, and following

1330-399: Is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day ). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in geosynchronous orbit returns to exactly the same position in the sky after a period of one sidereal day. Over the course of a day,

1400-426: Is available to hoist objects up the tether structure. Geosynchronous satellites require some station-keeping in order to remain in position, and once they run out of thruster fuel and are no longer useful they are moved into a higher graveyard orbit . It is not feasible to deorbit geosynchronous satellites, for to do so would take far more fuel than would be used by slightly elevating the orbit; and atmospheric drag

1470-401: Is negligible, giving GSOs lifetimes of thousands of years. The retirement process is becoming increasingly regulated and satellites must have a 90% chance of moving over 200 km above the geostationary belt at end of life. Space debris in geosynchronous orbits typically has a lower collision speed than at LEO since most GSO satellites orbit in the same plane, altitude and speed; however,

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1540-452: Is that of the launch site's latitude, so launching the satellite from close to the equator limits the amount of inclination change needed later. Additionally, launching from close to the equator allows the speed of the Earth's rotation to give the satellite a boost. A launch site should have water or deserts to the east, so any failed rockets do not fall on a populated area. Most launch vehicles place geostationary satellites directly into

1610-453: Is that of the launch site's latitude, so launching the satellite from close to the equator limits the amount of inclination change needed later. Additionally, launching from close to the equator allows the speed of the Earth's rotation to give the satellite a boost. A launch site should have water or deserts to the east, so any failed rockets do not fall on a populated area. Most launch vehicles place geosynchronous satellites directly into

1680-403: Is the gravitational constant , (6.674 28 ± 0.000 67 ) × 10  m kg s . The magnitude of the acceleration, a , of a body moving in a circle is given by: where v is the magnitude of the velocity (i.e. the speed) of the satellite. From Newton's second law of motion , the centripetal force F c is given by: As F c = F g , so that Replacing v with the equation for

1750-781: Is typically 70°, and in some cases less. Geostationary satellite imagery has been used for tracking volcanic ash , measuring cloud top temperatures and water vapour, oceanography , measuring land temperature and vegetation coverage, facilitating cyclone path prediction, and providing real time cloud coverage and other tracking data. Some information has been incorporated into meteorological prediction models , but due to their wide field of view, full-time monitoring and lower resolution, geostationary weather satellite images are primarily used for short-term and real-time forecasting. Geostationary satellites can be used to augment GNSS systems by relaying clock , ephemeris and ionospheric error corrections (calculated from ground stations of

1820-408: Is used to provide visible and infrared images of Earth's surface and atmosphere for weather observation, oceanography , and atmospheric tracking. As of 2019 there are 19 satellites in either operation or stand-by. These satellite systems include: These satellites typically capture images in the visual and infrared spectrum with a spatial resolution between 0.5 and 4 square kilometres. The coverage

1890-806: The O3b and O3b mPOWER constellations for low- latency broadband and data backhaul to maritime, aero and remote locations (with an altitude of 8,063 kilometres, 5,010 mi). Communications satellites to cover the North and South Pole are also put in MEO. Telstar 1, an experimental communications satellite launched in 1962, orbited in MEO. In May 2022, Kazakhstani mobile network operator, Kcell , and satellite owner and operator, SES used SES's O3b MEO satellite constellation to demonstrate that MEO satellites could be used to provide high-speed mobile internet to remote regions of Kazakhstan for reliable video calling, conferencing and streaming, and web browsing, with

1960-481: The Radio Regulations . In the 1976 Bogota Declaration , eight countries located on the Earth's equator claimed sovereignty over the geostationary orbits above their territory, but the claims gained no international recognition. A statite is a hypothetical satellite that uses radiation pressure from the sun against a solar sail to modify its orbit. It would hold its location over the dark side of

2030-490: The Van Allen radiation belts , which can damage satellites’ electronic systems without special shielding. A medium Earth orbit is sometimes called mid Earth orbit or intermediate circular orbit ( ICO ). Two medium Earth orbits are particularly significant. A satellite in the semi-synchronous orbit at an altitude of approximately 20,200 kilometres (12,600 mi) has an orbital period of 12 hours and passes over

2100-430: The centripetal force required to maintain the orbit ( F c ) is equal to the gravitational force acting on the satellite ( F g ): From Isaac Newton 's universal law of gravitation , where F g is the gravitational force acting between two objects, M E is the mass of the Earth, 5.9736 × 10  kg , m s is the mass of the satellite, r is the distance between the centers of their masses , and G

2170-451: The direction of Earth's rotation . An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day , and so to ground observers it appears motionless, in a fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C. Clarke in the 1940s as a way to revolutionise telecommunications, and the first satellite to be placed in this kind of orbit

Medium Earth orbit - Misplaced Pages Continue

2240-424: The Earth at a latitude of approximately 30 degrees. A statite is stationary relative to the Earth and Sun system rather than compared to surface of the Earth, and could ease congestion in the geostationary ring. Geostationary satellites require some station keeping to keep their position, and once they run out of thruster fuel they are generally retired. The transponders and other onboard systems often outlive

2310-498: The US and Europe was then possible between just 136 people at a time, and reliant on high frequency radios and an undersea cable . Conventional wisdom at the time was that it would require too much rocket power to place a satellite in a geosynchronous orbit and it would not survive long enough to justify the expense, so early efforts were put towards constellations of satellites in low or medium Earth orbit. The first of these were

2380-711: The World. Subsequently, in February 2024, SES announced that Virgin Voyages will be the first cruise line to deploy the service. Space debris in medium Earth orbit stays practically permanently orbiting Earth. Most space debris extends to the lowest high Earth orbits just beyond the edge of medium Earth orbit, where geostationary satellites are and where after their end of use they are parked in similar orbits, so-called graveyard orbits . Geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO )

2450-400: The absence of servicing missions from the Earth or a renewable propulsion method, the consumption of thruster propellant for station-keeping places a limitation on the lifetime of the satellite. Hall-effect thrusters , which are currently in use, have the potential to prolong the service life of a satellite by providing high-efficiency electric propulsion . For circular orbits around a body,

2520-458: The concept was seen as impractical, so Hughes often withheld funds and support. By 1961, Rosen and his team had produced a cylindrical prototype with a diameter of 76 centimetres (30 in), height of 38 centimetres (15 in), weighing 11.3 kilograms (25 lb), light and small enough to be placed into orbit. It was spin stabilised with a dipole antenna producing a pancake shaped beam. In August 1961, they were contracted to begin building

2590-548: The connection in his introduction to The Complete Venus Equilateral . The orbit, which Clarke first described as useful for broadcast and relay communications satellites, is sometimes called the Clarke Orbit. Similarly, the collection of artificial satellites in this orbit is known as the Clarke Belt. In technical terminology, the geosynchronous orbits are often referred to as geostationary if they are roughly over

2660-481: The connection in his introduction to The Complete Venus Equilateral . The orbit, which Clarke first described as useful for broadcast and relay communications satellites, is sometimes called the Clarke orbit. Similarly, the collection of artificial satellites in this orbit is known as the Clarke Belt. In technical terminology the orbit is referred to as either a geostationary or geosynchronous equatorial orbit, with

2730-493: The desired longitude, the spacecraft's period is restored to geosynchronous. A statite is a hypothetical satellite that uses radiation pressure from the Sun against a solar sail to modify its orbit. It would hold its location over the dark side of the Earth at a latitude of approximately 30 degrees. It would return to the same spot in the sky every 24 hours from an Earth-based viewer's perspective, so be functionally similar to

2800-646: The end of the satellite's lifetime, when fuel approaches depletion, satellite operators may decide to omit these expensive manoeuvres to correct inclination and only control eccentricity. This prolongs the life-time of the satellite as it consumes less fuel over time, but the satellite can then only be used by ground antennas capable of following the N-S movement. Geostationary satellites will also tend to drift around one of two stable longitudes of 75° and 255° without station keeping. Many objects in geosynchronous orbits have eccentric and/or inclined orbits. Eccentricity makes

2870-659: The equator and appear lower in the sky to an observer nearer the poles. As the observer's latitude increases, communication becomes more difficult due to factors such as atmospheric refraction , Earth's thermal emission , line-of-sight obstructions, and signal reflections from the ground or nearby structures. At latitudes above about 81°, geostationary satellites are below the horizon and cannot be seen at all. Because of this, some Russian communication satellites have used elliptical Molniya and Tundra orbits, which have excellent visibility at high latitudes. A worldwide network of operational geostationary meteorological satellites

Medium Earth orbit - Misplaced Pages Continue

2940-477: The equator, but the terms are used somewhat interchangeably. Specifically, geosynchronous Earth orbit ( GEO ) may be a synonym for geosynchronous equatorial orbit , or geostationary Earth orbit . The first geosynchronous satellite was designed by Harold Rosen while he was working at Hughes Aircraft in 1959. Inspired by Sputnik 1 , he wanted to use a geostationary (geosynchronous equatorial) satellite to globalise communications. Telecommunications between

3010-474: The equilibrium points would (without any action) be slowly accelerated towards the stable equilibrium position, causing a periodic longitude variation. The correction of this effect requires station-keeping maneuvers with a maximal delta-v of about 2 m/s per year, depending on the desired longitude. Solar wind and radiation pressure also exert small forces on satellites: over time, these cause them to slowly drift away from their prescribed orbits. In

3080-489: The following properties: All geosynchronous orbits have an orbital period equal to exactly one sidereal day. This means that the satellite will return to the same point above the Earth's surface every (sidereal) day, regardless of other orbital properties. This orbital period, T, is directly related to the semi-major axis of the orbit through the formula: where: A geosynchronous orbit can have any inclination. Satellites commonly have an inclination of zero, ensuring that

3150-553: The following properties: An inclination of zero ensures that the orbit remains over the equator at all times, making it stationary with respect to latitude from the point of view of a ground observer (and in the Earth-centered Earth-fixed reference frame). The orbital period is equal to exactly one sidereal day. This means that the satellite will return to the same point above the Earth's surface every (sidereal) day, regardless of other orbital properties. For

3220-523: The ground. All geostationary satellites have to be located on this ring. A combination of lunar gravity, solar gravity, and the flattening of the Earth at its poles causes a precession motion of the orbital plane of any geostationary object, with an orbital period of about 53 years and an initial inclination gradient of about 0.85° per year, achieving a maximal inclination of 15° after 26.5 years. To correct for this perturbation , regular orbital stationkeeping maneuvers are necessary, amounting to

3290-400: The lowest MEO altitude) about 2 hours. Satellites in MEO orbits are perturbed by solar radiation pressure, which is the dominating non-gravitational perturbing force. Other perturbing forces include: Earth's albedo , navigation antenna thrust, and thermal effects related to heat re-radiation. The MEO region includes the two zones of energetic charged particles above the equator known as

3360-515: The object's position in the sky may remain still or trace out a path, typically in a figure-8 form , whose precise characteristics depend on the orbit's inclination and eccentricity . A circular geosynchronous orbit has a constant altitude of 35,786 km (22,236 mi). A special case of geosynchronous orbit is the geostationary orbit (often abbreviated GEO ), which is a circular geosynchronous orbit in Earth's equatorial plane with both inclination and eccentricity equal to 0. A satellite in

3430-438: The orbit elliptical and appear to oscillate E-W in the sky from the viewpoint of a ground station, while inclination tilts the orbit compared to the equator and makes it appear to oscillate N-S from a groundstation. These effects combine to form an analemma (figure-8). Satellites in elliptical/eccentric orbits must be tracked by steerable ground stations . The Tundra orbit is an eccentric geosynchronous orbit, which allows

3500-450: The orbit remains over the equator at all times, making it stationary with respect to latitude from the point of view of a ground observer (and in the ECEF reference frame). Another popular inclinations is 63.4° for a Tundra orbit, which ensures that the orbit's argument of perigee does not change over time. In the special case of a geostationary orbit, the ground track of a satellite

3570-489: The passive Echo balloon satellites in 1960, followed by Telstar 1 in 1962. Although these projects had difficulties with signal strength and tracking that could be solved through geosynchronous satellites, the concept was seen as impractical, so Hughes often withheld funds and support. By 1961, Rosen and his team had produced a cylindrical prototype with a diameter of 76 centimetres (30 in), height of 38 centimetres (15 in), weighing 11.3 kilograms (25 lb); it

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3640-476: The planet now have terrestrial communications facilities ( microwave , fiber-optic ), with telephone access covering 96% of the population and internet access 90%, some rural and remote areas in developed countries are still reliant on satellite communications. Most commercial communications satellites , broadcast satellites and SBAS satellites operate in geostationary orbits. Geostationary communication satellites are useful because they are visible from

3710-552: The population and internet access 90% as of 2018, some rural and remote areas in developed countries are still reliant on satellite communications. A geostationary equatorial orbit (GEO) is a circular geosynchronous orbit in the plane of the Earth's equator with a radius of approximately 42,164 km (26,199 mi) (measured from the center of the Earth). A satellite in such an orbit is at an altitude of approximately 35,786 km (22,236 mi) above mean sea level. It maintains

3780-450: The presence of satellites in eccentric orbits allows for collisions at up to 4 km/s. Although a collision is comparatively unlikely, GSO satellites have a limited ability to avoid any debris. Debris less than 10 cm in diameter cannot be seen from the Earth, making it difficult to assess their prevalence. Despite efforts to reduce risk, spacecraft collisions have occurred. The European Space Agency telecom satellite Olympus-1

3850-640: The real satellite. They lost Syncom 1 to electronics failure, but Syncom 2 was successfully placed into a geosynchronous orbit in 1963. Although its inclined orbit still required moving antennas, it was able to relay TV transmissions, and allowed for US President John F. Kennedy in Washington D.C., to phone Nigerian prime minister Abubakar Tafawa Balewa aboard the USNS Kingsport docked in Lagos on August 23, 1963. The first satellite placed in

3920-524: The same plane, altitude and speed; however, the presence of satellites in eccentric orbits allows for collisions at up to 4 km/s. Although a collision is comparatively unlikely, GEO satellites have a limited ability to avoid any debris. At geosynchronous altitude, objects less than 10 cm in diameter cannot be seen from the Earth, making it difficult to assess their prevalence. Despite efforts to reduce risk, spacecraft collisions have occurred. The European Space Agency telecom satellite Olympus-1

3990-418: The same position relative to the Earth's surface. If one could see a satellite in geostationary orbit, it would appear to hover at the same point in the sky, i.e., not exhibit diurnal motion , while the Sun, Moon, and stars would traverse the skies behind it. Such orbits are useful for telecommunications satellites . A perfectly stable geostationary orbit is an ideal that can only be approximated. In practice

4060-528: The same two spots on the equator every day. This reliably predictable orbit is used by the Global Positioning System (GPS) constellation . Other navigation satellite systems use similar medium Earth orbits including GLONASS (with an altitude of 19,100 kilometres, 11,900 mi), Galileo (with an altitude of 23,222 kilometres, 14,429 mi) and BeiDou (with an altitude of 21,528 kilometres, 13,377 mi). The Molniya orbit has

4130-478: The satellite drifts out of this orbit because of perturbations such as the solar wind , radiation pressure , variations in the Earth's gravitational field, and the gravitational effect of the Moon and Sun , and thrusters are used to maintain the orbit in a process known as station-keeping . Eventually, without the use of thrusters, the orbit will become inclined, oscillating between 0° and 15° every 55 years. At

4200-500: The satellite to spend most of its time dwelling over one high latitude location. It sits at an inclination of 63.4°, which is a frozen orbit , which reduces the need for stationkeeping . At least two satellites are needed to provide continuous coverage over an area. It was used by the Sirius XM Satellite Radio to improve signal strength in the northern US and Canada. The Quasi-Zenith Satellite System (QZSS)

4270-405: The sky. A geostationary orbit can be achieved only at an altitude very close to 35,786 kilometres (22,236 miles) and directly above the equator. This equates to an orbital speed of 3.07 kilometres per second (1.91 miles per second) and an orbital period of 1,436 minutes, one sidereal day . This ensures that the satellite will match the Earth's rotational period and has a stationary footprint on

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4340-549: The special case of the geostationary Earth orbit in particular as useful orbits for space stations . The first appearance of a geosynchronous orbit in popular literature was in October 1942, in the first Venus Equilateral story by George O. Smith , but Smith did not go into details. British science fiction author Arthur C. Clarke popularised and expanded the concept in a 1945 paper entitled Extra-Terrestrial Relays – Can Rocket Stations Give Worldwide Radio Coverage? , published in Wireless World magazine. Clarke acknowledged

4410-444: The terms used somewhat interchangeably. The first geostationary satellite was designed by Harold Rosen while he was working at Hughes Aircraft in 1959. Inspired by Sputnik 1 , he wanted to use a geostationary satellite to globalise communications. Telecommunications between the US and Europe was then possible between just 136 people at a time, and reliant on high frequency radios and an undersea cable . Conventional wisdom at

4480-485: The thruster fuel and by allowing the satellite to move naturally into an inclined geosynchronous orbit some satellites can remain in use, or else be elevated to a graveyard orbit . This process is becoming increasingly regulated and satellites must have a 90% chance of moving over 200 km above the geostationary belt at end of life. Space debris at geostationary orbits typically has a lower collision speed than at low Earth orbit (LEO) since all GEO satellites orbit in

4550-501: The time was that it would require too much rocket power to place a satellite in a geostationary orbit and it would not survive long enough to justify the expense, so early efforts were put towards constellations of satellites in low or medium Earth orbit. The first of these were the passive Echo balloon satellites in 1960, followed by Telstar 1 in 1962. Although these projects had difficulties with signal strength and tracking, issues that could be solved using geostationary orbits,

4620-511: Was able to relay TV transmissions, and allowed for US President John F. Kennedy to phone Nigerian prime minister Abubakar Tafawa Balewa from a ship on August 23, 1963. Today there are hundreds of geosynchronous satellites providing remote sensing , navigation and communications. Although most populated land locations on the planet now have terrestrial communications facilities ( microwave , fiber-optic ), which often have latency and bandwidth advantages, and telephone access covering 96% of

4690-494: Was launched in 1963. Communications satellites are often placed in a geostationary orbit so that Earth-based satellite antennas do not have to rotate to track them but can be pointed permanently at the position in the sky where the satellites are located. Weather satellites are also placed in this orbit for real-time monitoring and data collection, and navigation satellites to provide a known calibration point and enhance GPS accuracy. Geostationary satellites are launched via

4760-430: Was light, and small, enough to be placed into orbit by then-available rocketry, was spin stabilised and used dipole antennas producing a pancake-shaped waveform. In August 1961, they were contracted to begin building the working satellite. They lost Syncom 1 to electronics failure, but Syncom 2 was successfully placed into a geosynchronous orbit in 1963. Although its inclined orbit still required moving antennas, it

4830-491: Was struck by a meteoroid on August 11, 1993, and eventually moved to a graveyard orbit , and in 2006 the Russian Express-AM11 communications satellite was struck by an unknown object and rendered inoperable, although its engineers had enough contact time with the satellite to send it into a graveyard orbit. In 2017 both AMC-9 and Telkom-1 broke apart from an unknown cause. A geosynchronous orbit has

4900-427: Was struck by a meteoroid on August 11, 1993, and eventually moved to a graveyard orbit , and in 2006 the Russian Express-AM11 communications satellite was struck by an unknown object and rendered inoperable, although its engineers had enough contact time with the satellite to send it into a graveyard orbit. In 2017, both AMC-9 and Telkom-1 broke apart from an unknown cause. A typical geostationary orbit has

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